An inventive medical imaging marker includes a base (2) composed of a non-imageable material, three spherical members (10, 11, 12) provided in a predetermined positional relationship in the base (2) and each composed of an imageable material, and auxiliary marker members (20, 21, 22) provided in the base (2) and composed of the imageable material. The auxiliary marker members (20, 21, 22) respectively have linear portions (20L, 21L, 22L) which are disposed parallel to straight lines extending through center points of the three spherical members (10, 11, 12) and each have a predetermined length sufficient to serve as a mark. The center points of the three spherical members (10, 11, 12) can be correctly identified in a captured image with reference to the linear portions (20L, 21L, 22L) of the auxiliary marker members (20, 21, 22) of the inventive medical imaging marker. Thus, reference axes can be correctly defined in the image.
